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diff --git a/demos/quickstart/protected/pages/Database/ActiveRecord.page b/demos/quickstart/protected/pages/Database/ActiveRecord.page new file mode 100644 index 00000000..017b8d45 --- /dev/null +++ b/demos/quickstart/protected/pages/Database/ActiveRecord.page @@ -0,0 +1,360 @@ +<com:TContent ID="body" > +<!-- $Id $ --> +<h1>Active Record</h1> +<p>Active Records are objects that wrap a row in a database table or view, + encapsulates the database access and adds domain logic on that data. + The basics of an Active Record is a business object class, e.g., a + <tt>Products</tt> class, that match very closely the record structure + of an underlying database table. Each Active Record will be responsible for + saving and loading data to and from the database. </p> +<div class="info"><b class="note">Info:</b> + The data structure of an Active Record should match exactly that of a table + in the database. + Each field in the class must correspond to one column in the table. +</div> + +<h2>When to Use It</h2> +<p>Active Record is a good choice for domain logic that isn't too complex, + such as creates, reads, updates, and deletes. Derivations and validations + based on a single record work well in this structure. Active Record has the + primary advantage of simplicity. It's easy to build + Active Records, and they are easy to understand.</p> + + <p>However, as your business logic grows in complexity, you'll soon want + to use your object's direct relationships, collections, inheritance, and so + forth. These don't map easily onto Active Record, and adding them piecemeal + gets very messy. + Another argument against Active Record is the fact that it couples the object + design to the database design. This makes it more difficult to refactor as a project goes forward.</p> + + <p>The alternative is to use a Data Mapper that separates the roles of the + business object and how these objects are stored. + Prado provides a complimentary choice between Active Record and + <a href="?page=Database.SqlMap">SqlMap Data Mapper</a>. + A SqlMap Data Mapper can be used to load Active Record objects, in turn, these + Active Record objects can be used to update the database. + The "relationship" between Active Records and <a href="?page=Database.SqlMap">SqlMap</a> is illustrated in the + following diagram. More details regarding the SqlMap Data Mapper can be found in + the <a href="http://www.pradosoft.com/demos/sqlmap/">SqlMap Manual</a>. + <img src=<%~ sqlmap_active_record.png %> alt="Active Records and SqlMap DataMapper" id="fig:diagram.png" class="figure"/> + </p> + + <p> + The Active Record class has methods that do the following: + <ul> + <li>Construct an instance of the Active Record from a SQL result set row.</li> + <li>Construct a new instance for later insertion into the table.</li> + <li>Finder methods to wrap commonly used SQL queries and return Active Record objects.</li> + <li>Update existing records and insert new records into the database.</li> + </ul> + </p> +The Active Record implementation utilizes the <a href="?page=Database.DAO">Prado DAO</a> classes for data access. +The current Active Record implementation supports +<a href="http://www.mysql.com">MySQL</a>, +<a href="http://www.postgres.com">Postgres SQL</a> and +<a href="http://www.sqlite.org">SQLite</a> databases. +Support for other databases can be provided when there are sufficient demand. +<h2>Defining an Active Record</h2> +<p>Let us + consider the following "users" table that contains two columns named "username" and "email", + where "username" is also the primary key. +<com:TTextHighlighter Language="sql" CssClass="source"> +CREATE TABLE users +( + username VARCHAR( 20 ) NOT NULL , + email VARCHAR( 200 ) , + PRIMARY KEY ( username ) +); +</com:TTextHighlighter> +</p> +<p>Next we define our Active Record class that corresponds to the "users" table. +<com:TTextHighlighter Language="php" CssClass="source"> +class UserRecord extends TActiveRecord +{ + public $username; //the column named "username" in the "users" table + public $email; + + private static $_tablename='users'; //table name + + /** + * @return TActiveRecord active record finder instance + */ + public static function finder() + { + return self::getRecordFinder('UserRecord'); + } +} +</com:TTextHighlighter> +</p> +<p>Each property of the <tt>UserRecord</tt> class must correspond to a + column with the same name in the "users" table. The static class variable + <tt>$_tablename</tt> is optional when the class name is the same as + the table name in the database, otherwise <tt>$_tablename</tt> must + specify the table name that corresponds to your Active Record class. +</p> + +<div class="tip"><b class="note">Tip:</b> + Since <tt>TActiveRecord</tt> extends <tt>TComponent</tt>, setter and + getter methods can be defined to allow control over how variables + are set and returned. For example, adding a <tt>$level</tt> property to the UserRecord class: +<com:TTextHighlighter Language="php" CssClass="source"> +class UserRecord extends TActiveRecord { + ... //existing definitions as above + + private $_level; + public function setLevel($value) { + $this->_level=TPropertyValue::ensureInteger($value,0); + } + public function getLevel($value){ + return $this->_level; + } +} +</com:TTextHighlighter> +</div> + +<p> + The static method <tt>finder()</tt> returns an <tt>UserRecord</tt> instance + that can be used to load records from the database. The loading of records + using the finer methods is discuss a little later. The <tt>TActiveRecord::getRecordFinder()</tt> + static method takes the name of the current Active Record class as parameter. +</p> + +<h2>Setting up a database connection</h2> +<p> + A default database connection for Active Record can be set as follows. + See <a href="?page=Database.DAO">Establishing Database Connection</a> for + futher details regarding creation of database connection in general. +<com:TTextHighlighter Language="php" CssClass="source"> +//create a connection and give it to the ActiveRecord manager. +$dsn = 'pgsql:host=localhost;dbname=test'; //Postgres SQL +$conn = new TDbConnection($dsn, 'dbuser','dbpass'); +TActiveRecordManager::getInstance()->setDbConnection($conn); +</com:TTextHighlighter> +</p> + +<p> + The default database connection can also be configured using a <tt><module></tt> + tag in the <a href="?page=Configurations.AppConfig">application.xml</a> + or <a href="?page=Configurations.PageConfig">config.xml</a> as follows. +<com:TTextHighlighter Language="xml" CssClass="source"> +<modules> + <module class="System.Data.ActiveRecord.TActiveRecordConfig" EnableCache="true"> + <database ConnectionString="pgsql:host=localhost;dbname=test" + Username="dbuser" Password="dbpass" /> + </module> +</modules> +</com:TTextHighlighter> +<div class="tip"><b class="note">Tip:</b> + The <tt>EnableCache</tt> attribute when set to "true" will cache the table + meta data, that is, the table columns names, indexes and constraints are + saved in the cache and reused. You must clear or disable the cache if you + wish to see chanages made to your table definitions. A <a href="?page=Advanced.Performance#6402">cache + module</a> must also be defined for the cache to function. +</div> +</p> + +<p>A <tt>ConnectionID</tt> property can be specified with value corresponding + to another <tt>TDataSourceConfig</tt> module configuration's ID value. This allows + the same database connection to be used in other modules such as <a href="?page=Database.SqlMap">SqlMap</a>. +<com:TTextHighlighter Language="xml" CssClass="source"> +<modules> + <module class="System.Data.TDataSourceConfig" ID="db1"> + <database ConnectionString="pgsql:host=localhost;dbname=test" + Username="dbuser" Password="dbpass" /> + </module> + + <module class="System.Data.ActiveRecord.TActiveRecordConfig" + ConnectionID="db1" EnableCache="true" /> + + <module class="System.Data.SqlMap.TSqlMapConfig" + ConnectionID="db1" ... /> +</modules> +</com:TTextHighlighter> +</p> + +<h2>Loading data from the database</h2> +<p> + The <tt>TActiveRecord</tt> class provides many convenient methods to find + records from the database. The simplest is finding records by matching primary keys. + See the <com:DocLink ClassPath="System.Data.ActiveRecord.TActiveRecord" /> for + more details. +</p> + <h3><tt>findByPk()</tt></h3> + <p>Finds one record using only the primary key or composite primary keys. +<com:TTextHighlighter Language="php" CssClass="source"> +$finder = UserRecord::finder(); +$user = $finder->findByPk($primaryKey); + +//when the table uses composite keys +$record = $finder->findByPk($key1, $key2, ...); //for composite keys +$record = $finder->findByPk(array($key1, $key2,...)); //same as above +</com:TTextHighlighter> +</p> + +<h3><tt>find()</tt></h3> +<p>Finds <b>one single record</b> that matches the criteria. The criteria + can be a partial SQL string or a <tt>TActiveRecordCriteria</tt> object. +<com:TTextHighlighter Language="php" CssClass="source"> +$finder = UserRecord::finder(); + +//:name and :pass are place holders for specific values of $name and $pass +$finder->find('username = :name AND password = :pass', + array(':name'=>$name, ':pass'=>$pass)); + +//using position place holders +$finder->find('username = ? AND password = ?', array($name, $pass)); +//same as above +$finder->find('username = ? AND password = ?', $name, $pass); + +//$criteria is of TActiveRecordCriteria +$finder->find($criteria); //the 2nd parameter for find() is ignored. +</com:TTextHighlighter> +</p> + +<p>The <tt>TActiveRecordCriteria</tt> class has the following properties: + <ul> + <li><tt>Parameters</tt> -- name value parameter pairs.</li> + <li><tt>OrderBy</tt> -- column name and ordering pairs.</li> + <li><tt>Condition</tt> -- parts of the WHERE SQL conditions.</li> + <li><tt>Limit</tt> -- maximum number of records to return.</li> + <li><tt>Offset</tt> -- record offset in the table.</li> + </ul> +</p> + +<com:TTextHighlighter Language="php" CssClass="source"> +$criteria = new TActiveRecordCriteria; +$criteria->Condition = 'username = :name AND password = :pass'; +$criteria->Parameters[':name'] = 'admin'; +$criteria->Parameters[':pass'] = 'prado'; +$criteria->OrdersBy['level'] = 'desc'; +$criteria->OrdersBy['name'] = 'asc'; +$criteria->Limit = 10; +$criteria->Offset = 20; +</com:TTextHighlighter> + +<h3><tt>findAll()</tt></h3> +<p>Same as <tt>find()</tt> but returns an array of objects.</p> + +<h3><tt>findBy*()</tt> and <tt>findAllBy*()</tt></h3> +<p>Dynamic find method using parts of method name as search criteria. +Method names starting with <tt>findBy</tt> return 1 record only. +Method names starting with <tt>findAllBy</tt> return an array of records. +The condition is taken as part of the method name after <tt>findBy</tt> or <tt>findAllBy</tt>. + +The following blocks of code are equivalent: + +<com:TTextHighlighter Language="php" CssClass="source"> +$finder->findByName($name) +$finder->find('Name = ?', $name); +</com:TTextHighlighter> + +<com:TTextHighlighter Language="php" CssClass="source"> +$finder->findByUsernameAndPassword($name,$pass); +$finder->findBy_Username_And_Password($name,$pass); +$finder->find('Username = ? AND Password = ?', $name, $pass); +</com:TTextHighlighter> + +<com:TTextHighlighter Language="php" CssClass="source"> +$finder->findAllByAge($age); +$finder->findAll('Age = ?', $age); +</com:TTextHighlighter> +</p> + +<h3><tt>findBySql()</tt></h3> +<p>Finds records using full SQL, returns corresponding array of record objects.</p> + +<h3><tt>count()</tt></h3> +<p>Find the number of matchings records.</p> + +<h2>Inserting and updating records</h2> +<p> +Add a new record using TActiveRecord is very simple, just create a new Active +Record object and call the <tt>save()</tt> method. E.g. +<com:TTextHighlighter Language="php" CssClass="source"> +$user1 = new UserRecord(); +$user1->username = "admin" +$user1->email = "admin@example.com"; +$user1->save(); //insert a new record + +$data = array('username'=>'admin', 'email'=>'admin@example.com'); +$user2 = new UserRecord($data); //create by passing some existing data +$user2->save(); //insert a new record +</com:TTextHighlighter> +<div class="tip"><b class="note">Tip:</b> +The objects are update with the primary key of those the tables that contains +definitions that automatically creates a primary key for the newly insert records. +For example, if you insert a new record into a MySQL table that has columns +defined with "autoincrement", the Active Record objects will be updated with the new +incremented values.</div> +</p> + +<p> +To update a record in the database, just change one or more properties of +the Active Record object that has been loaded from the database and then +call the <tt>save()</tt> method. + +<com:TTextHighlighter Language="php" CssClass="source"> +$user = UserRecord::finder()->findByName('admin'); +$user->email="test@example.com"; //change property +$user->save(); //update it. +</com:TTextHighlighter> +</p> + +<p> +Active Record objects have a simple life-cycle illustrated in the following diagram. +<img src=<%~ object_states.png %> alt="Active Records Life Cycle" id="fig:cycle.png" class="figure"/> +</p> + +<h2>Deleting existing records</h2> +<p> + To delete an existing record that is already loaded, just call the <tt>delete()</tt> method. + You can also delete records in the database by primary keys without + loading any records using the <tt>deleteByPk()</tt> method. + For example, to delete one or records with tables having a scalar primary key. +<com:TTextHighlighter Language="php" CssClass="source"> +$finder->deleteByPk($primaryKey); //delete 1 record +$finder->deleteByPk($key1,$key2,...); //delete multiple records +$finder->deleteByPk(array($key1,$key2,...)); //delete multiple records +</com:TTextHighlighter> +</p> + +<p> +For composite primary keys (determined automatically from the table definitions): +<com:TTextHighlighter Language="php" CssClass="source"> +$finder->deleteByPk(array($key1,$key2)); //delete 1 record + +//delete multiple records +$finder->deleteByPk(array($key1,$key2), array($key3,$key4),...); + +//delete multiple records +$finder->deleteByPk(array( array($key1,$key2), array($key3,$key4), .. )); +</com:TTextHighlighter> +</p> + +<h2>Transactions</h2> +<p>All Active Record objects contains the property <tt>DbConnection</tt> + that can be used to obtain a transaction object. +<com:TTextHighlighter Language="php" CssClass="source"> +$finder = UserRecord::finder(); + +$transaction = $finder->DbConnection->beginTransaction(); +try +{ + $user = $finder->findByPk('admin'); + $user->email = 'test@example.com'; //alter the $user object + $user->save(); + $transaction->commit(); +} +catch(Exception $e) // an exception is raised if a query fails will be raised +{ + $transaction->rollBack(); +} +</com:TTextHighlighter> + +<h2>References</h2> +<ul> + <li>Fowler et. al. <i>Patterns of Enterprise Application Architecture</i>, + Addison Wesley, 2002.</li> +</ul> + +</com:TContent>
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